This invention relates to a system for cancelling or substantially reducing the noise from a noise source received, for example, by an individual.
It is well known that loud noise levels can make a person in the noise environment uncomfortable and, in fact, it can produce permanent damage to the ears of the person. This problem is particularly serious where a person or persons are required to work near noisy machinery.
Arrangements have been proposed in the past for cancelling some of the noise by producing an anti-noise signal which combines with the undesired noise. However, in the past such noise cancellation arrangements have been proposed mainly for well structured noise, that is, noise having a consistent, mostly deterministic noise pattern, and they have not been particularly effective.
It is a general object of the present invention to provide an improved system for substantially reducing the noise level in a noise environment, which is more effective than prior art proposals and is also effective with highly chaotic stochastic noise, and where the noise residual is driven towards a white noise sequence of difference between the original noise and the anti-noise.